NDS32/opcodes: Add audio ISA extension and modify the disassemble implemnt.

NDS32/opcodes: Add audio ISA extension and modify the disassemble implemnt.

First, add nds32 audio ISA extension including opcodes and registers.
Second, redesign the disassemble implement.
The original disassemble decode instruction opcode using switch-case.
It is hard to synchronize when adding new instructions.
Therefore, the new implement reuses nds32_opcodes to dump the instructions.